Most everyone knows about the notorious transmission bottleneck in the state of California: the Path 15 section of the state’s north and south link between the Bay Area and Los Angeles. Built to combat power-reliability problems in the Golden State, the Path 15 500-kV transmission line connecting Southern California with the northern part of the state is now in service, after it was first announced on Oct. 18, 2001.

Expected to provide 1500 MW, creating a combined system of 5400 MW or enough electricity to power 1.5 million homes, the Path 15 line was energized for testing on Dec. 7, 2004, and released for commercial operation 14 days later.

Western Area Power Administration (Western; Lakewood, Colorado, U.S.) managed construction and will own and operate the new 135-km (84-mile) line. Maslonka & Associates (Mesa, Arizona, U.S.) was the prime contractor.

Trans-Elect (Reston, Virginia, U.S.) arranged financing for the US$250-million public-private partnership project, which was 18% under the original $306-million budget. Trans-Elect’s public and private partners are Western, who will control 10% of the project, and Pacific Gas & Electric Co. (PG&E; San Francisco, California), who will be responsible for substation construction, representing another 10% of the project.

To accommodate the new high- voltage system, PG&E built new substations and reinforced existing 115- and 230-kV lines tying into the new one.

Erickson Air-Crane (Central Point, Oregon, U.S.) was the helicopter contractor and Burns & McDonnell (Kansas City, Missouri, U.S.) performed substation modifications engineering.

Statistics

A number of statistics were accumulated as a result of the projects:
� Insulators are 5.5 m (18 ft) long.
� 246 lattice towers and 98 steel poles were placed along the 135-km (84-mile) route.
� 1216 km (756 miles) of conductor and 270 km (168 miles) of overhead ground wire were strung.
� 8 million lb (3.6 million kg) of steel tubular material was delivered to staging yards.
� The average weight of each pole was 84,000 lb (38,102 kg).
� Structures range in height from 39 m to 62 m (130 ft to 205 ft).
� Three V-shaped insulators were mounted on each structure.
� 32 ball-and-socket porcelain insulators were attached on each span.
� 20,000 metallic diverters were installed on the conductors.

Other Highlights

In acquiring land rights and route selection, Western used aircraft-mounted light detection and ranging (LiDAR) system laser-beam technology to collect topographic data and ground coordinates.

Due to the large size of the tubular structures, the arms connections were much larger than usual, requiring specialized engineering and design by steel-pole provider Thomas & Betts/Meyer (Hager City, Wisconsin, U.S.). Steel structures were coated a medium gray using Sigma Coating’s Micaceous iron oxide zinc protective metallized coating to comply with the nonglare requirements. Bracket and bridge materials were delivered to staging yards located 5 minutes from the tower construction sites.

Modifications associated with the substation modifications and the 230-kV shunt capacitor work included installing new 500-kV circuit breakers at Gates Substation and modifications to its 500-kV bus.

The Path 15 upgrade was originally envisioned in the 1980s as part of the California-Oregon Transmission Project, a 563.2-km (350-mile) transmission corridor. l